[PATCH 1/4] soc: qcom: rpmh: Allow non-child devices to issue write commands

[Fenglin Wu]

Currently, the RPMH driver only allows child devices of the RPMH
controller to issue commands, as it assumes dev->parent points to the
RSC device.

There is a possibility that certain devices which are not children of
the RPMH controller want to send commands for special control at the
RPMH side. For example, in PMH0101 PMICs, there are bidirectional
level shifter (LS) peripherals, and each LS works with a pair of PMIC
GPIOs. The control of the LS, which is combined with the GPIO
configuration, is handled by RPMH firmware for sharing the resource
between different subsystems. From a hardware point of view, the LS
functionality is tied to a pair of PMIC GPIOs, so its control is more
suitable to be added in the pinctrl-spmi-gpio driver by adding the
level-shifter function. However, the pinctrl-spmi-gpio device is a
child device of the SPMI controller, not the RPMH controller.

This patch extends the RPMH driver to support write commands from any
device that has a pointer to the RPMH controller device:

1. Add rpmh_get_ctrlr_dev() to lookup controller via device tree
   phandle "qcom,rpmh"
2. Add new APIs: rpmh_write_async_ctrlr() and rpmh_write_ctrlr()
   that accept controller device pointer directly

With this change, the pinctrl-spmi-gpio driver is able to issue write
commands to the RPMH controller by using the controller device pointer,
and vote for enabling the level-shifter function.

Signed-off-by: Fenglin Wu <fenglin.wu@xxxxxxxxxxxxxxxx>
---
 drivers/soc/qcom/rpmh.c | 161 +++++++++++++++++++++++++++++++++++++++++++-----
 include/soc/qcom/rpmh.h |  21 +++++++
 2 files changed, 167 insertions(+), 15 deletions(-)

diff --git a/drivers/soc/qcom/rpmh.c b/drivers/soc/qcom/rpmh.c
index ca37da3dc2b1..9c7844434e9a 100644
--- a/drivers/soc/qcom/rpmh.c
+++ b/drivers/soc/qcom/rpmh.c
@@ -12,6 +12,7 @@
 #include <linux/lockdep.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
@@ -76,6 +77,21 @@ static struct rpmh_ctrlr *get_rpmh_ctrlr(const struct device *dev)
 	return &drv->client;
 }
 
+static struct rpmh_ctrlr *get_rpmh_ctrlr_from_dev(const struct device *ctrl_dev)
+{
+	struct rsc_drv *drv;
+
+	if (!ctrl_dev)
+		return ERR_PTR(-EINVAL);
+
+	drv = dev_get_drvdata(ctrl_dev);
+
+	if (!drv)
+		return ERR_PTR(-ENODEV);
+
+	return &drv->client;
+}
+
 void rpmh_tx_done(const struct tcs_request *msg)
 {
 	struct rpmh_request *rpm_msg = container_of(msg, struct rpmh_request,
@@ -156,23 +172,11 @@ static struct cache_req *cache_rpm_request(struct rpmh_ctrlr *ctrlr,
 	return req;
 }
 
-/**
- * __rpmh_write: Cache and send the RPMH request
- *
- * @dev: The device making the request
- * @state: Active/Sleep request type
- * @rpm_msg: The data that needs to be sent (cmds).
- *
- * Cache the RPMH request and send if the state is ACTIVE_ONLY.
- * SLEEP/WAKE_ONLY requests are not sent to the controller at
- * this time. Use rpmh_flush() to send them to the controller.
- */
-static int __rpmh_write(const struct device *dev, enum rpmh_state state,
-			struct rpmh_request *rpm_msg)
+static int __rpmh_write_direct(struct rpmh_ctrlr *ctrlr, enum rpmh_state state,
+			       struct rpmh_request *rpm_msg)
 {
-	struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
-	int ret = -EINVAL;
 	struct cache_req *req;
+	int ret = -EINVAL;
 	int i;
 
 	/* Cache the request in our store and link the payload */
@@ -193,6 +197,25 @@ static int __rpmh_write(const struct device *dev, enum rpmh_state state,
 	return ret;
 }
 
+/**
+ * __rpmh_write: Cache and send the RPMH request
+ *
+ * @dev: The device making the request
+ * @state: Active/Sleep request type
+ * @rpm_msg: The data that needs to be sent (cmds).
+ *
+ * Cache the RPMH request and send if the state is ACTIVE_ONLY.
+ * SLEEP/WAKE_ONLY requests are not sent to the controller at
+ * this time. Use rpmh_flush() to send them to the controller.
+ */
+static int __rpmh_write(const struct device *dev, enum rpmh_state state,
+			struct rpmh_request *rpm_msg)
+{
+	struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
+
+	return __rpmh_write_direct(ctrlr, state, rpm_msg);
+}
+
 static int __fill_rpmh_msg(struct rpmh_request *req, enum rpmh_state state,
 		const struct tcs_cmd *cmd, u32 n)
 {
@@ -271,6 +294,114 @@ int rpmh_write(const struct device *dev, enum rpmh_state state,
 }
 EXPORT_SYMBOL_GPL(rpmh_write);
 
+/**
+ * rpmh_get_ctrlr_dev: Get RPMH controller device from device tree
+ *
+ * @dev: Device with "qcom,rpmh" phandle property
+ *
+ * Returns: Pointer to RPMH controller device, with a devm action registered
+ * on @dev to release the reference when @dev is unbound.
+ */
+struct device *rpmh_get_ctrlr_dev(struct device *dev)
+{
+	struct device_node *rpmh_np;
+	struct platform_device *pdev;
+	int ret;
+
+	rpmh_np = of_parse_phandle(dev->of_node, "qcom,rpmh", 0);
+	if (!rpmh_np)
+		return ERR_PTR(-ENODEV);
+
+	pdev = of_find_device_by_node(rpmh_np);
+	of_node_put(rpmh_np);
+
+	if (!pdev)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	ret = devm_add_action_or_reset(dev, (void (*)(void *))put_device,
+				       &pdev->dev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return &pdev->dev;
+}
+EXPORT_SYMBOL_GPL(rpmh_get_ctrlr_dev);
+
+/**
+ * rpmh_write_async_ctrlr: Write RPMH commands with the controller device pointer
+ *
+ * @ctrl_dev: The RPMH controller device
+ * @state: Active/sleep set
+ * @cmd: The payload data
+ * @n: The number of elements in payload
+ *
+ * Write a set of RPMH commands, the order of commands is maintained
+ * and will be sent as a single shot.
+ */
+int rpmh_write_async_ctrlr(const struct device *ctrl_dev, enum rpmh_state state,
+			   const struct tcs_cmd *cmd, u32 n)
+{
+	struct rpmh_request *rpm_msg;
+	struct rpmh_ctrlr *ctrlr;
+	int ret;
+
+	ctrlr = get_rpmh_ctrlr_from_dev(ctrl_dev);
+	if (IS_ERR(ctrlr))
+		return PTR_ERR(ctrlr);
+
+	rpm_msg = kzalloc_obj(*rpm_msg, GFP_ATOMIC);
+	if (!rpm_msg)
+		return -ENOMEM;
+	rpm_msg->needs_free = true;
+
+	ret = __fill_rpmh_msg(rpm_msg, state, cmd, n);
+	if (ret) {
+		kfree(rpm_msg);
+		return ret;
+	}
+
+	return __rpmh_write_direct(ctrlr, state, rpm_msg);
+}
+EXPORT_SYMBOL_GPL(rpmh_write_async_ctrlr);
+
+/**
+ * rpmh_write_ctrlr: Write RPMH commands and block until response,
+ * with the controller device pointer
+ *
+ * @ctrlr_dev: The RPMH controller device
+ * @state: Active/sleep set
+ * @cmd: The payload data
+ * @n: The number of elements in @cmd
+ *
+ * May sleep. Do not call from atomic contexts.
+ */
+int rpmh_write_ctrlr(const struct device *ctrlr_dev, enum rpmh_state state,
+		     const struct tcs_cmd *cmd, u32 n)
+{
+	DECLARE_COMPLETION_ONSTACK(compl);
+	/* dev is unused in the synchronous non-batch path; pass NULL */
+	DEFINE_RPMH_MSG_ONSTACK(NULL, state, &compl, rpm_msg);
+	struct rpmh_ctrlr *ctrlr;
+	int ret;
+
+	ctrlr = get_rpmh_ctrlr_from_dev(ctrlr_dev);
+	if (IS_ERR(ctrlr))
+		return PTR_ERR(ctrlr);
+
+	ret = __fill_rpmh_msg(&rpm_msg, state, cmd, n);
+	if (ret)
+		return ret;
+
+	ret = __rpmh_write_direct(ctrlr, state, &rpm_msg);
+	if (ret)
+		return ret;
+
+	ret = wait_for_completion_timeout(&compl, RPMH_TIMEOUT_MS);
+	WARN_ON(!ret);
+	return (ret > 0) ? 0 : -ETIMEDOUT;
+}
+EXPORT_SYMBOL_GPL(rpmh_write_ctrlr);
+
 static void cache_batch(struct rpmh_ctrlr *ctrlr, struct batch_cache_req *req)
 {
 	unsigned long flags;
diff --git a/include/soc/qcom/rpmh.h b/include/soc/qcom/rpmh.h
index bdbee1a97d36..90ddcd7ca2fe 100644
--- a/include/soc/qcom/rpmh.h
+++ b/include/soc/qcom/rpmh.h
@@ -22,6 +22,14 @@ int rpmh_write_batch(const struct device *dev, enum rpmh_state state,
 
 void rpmh_invalidate(const struct device *dev);
 
+struct device *rpmh_get_ctrlr_dev(struct device *dev);
+
+int rpmh_write_async_ctrlr(const struct device *ctrl_dev, enum rpmh_state state,
+			   const struct tcs_cmd *cmd, u32 n);
+
+int rpmh_write_ctrlr(const struct device *ctrlr_dev, enum rpmh_state state,
+		     const struct tcs_cmd *cmd, u32 n);
+
 #else
 
 static inline int rpmh_write(const struct device *dev, enum rpmh_state state,
@@ -42,6 +50,19 @@ static inline void rpmh_invalidate(const struct device *dev)
 {
 }
 
+static inline struct device *rpmh_get_ctrlr_dev(struct device *dev)
+{ return ERR_PTR(-ENODEV); }
+
+static inline int rpmh_write_async_ctrlr(const struct device *ctrl_dev,
+					  enum rpmh_state state,
+					  const struct tcs_cmd *cmd, u32 n)
+{ return -ENODEV; }
+
+static inline int rpmh_write_ctrlr(const struct device *ctrlr_dev,
+				    enum rpmh_state state,
+				    const struct tcs_cmd *cmd, u32 n)
+{ return -ENODEV; }
+
 #endif /* CONFIG_QCOM_RPMH */
 
 #endif /* __SOC_QCOM_RPMH_H__ */

-- 
2.43.0